WHOWAS now returns history of recently-disconnected clients

QUIT and socket cleanup paths push a small (last 32) ring of
{nick, username, realname, host, ts} entries into a new :whowas
atom on the components map.  WHOWAS reads that ring case-
insensitively and answers with RPL_WHOWASUSER (314) +
RPL_WHOISSERVER (312) for each match, terminated with
RPL_ENDOFWHOWAS (369), or falls back to ERR_WASNOSUCHNICK (406)
when nothing is found.

3 files changed, 100 insertions, 9 deletions

diff --git a/src/papod.clj b/src/papod.clj
index eb4d6fa..21999e9 100644
--- a/src/papod.clj
+++ b/src/papod.clj
@@ -2746,6 +2746,19 @@
         (let [nick    (client-target client)
               reason  (or (first params) "Client quit")
               {:keys [clients channels]} components]
+          ;; Record WHOWAS entry for registered clients
+          (when (and (:registered? @client)
+                     (:whowas components))
+            (let [u (:user @client)]
+              (swap! (:whowas components)
+                     (fn [hist]
+                       (let [entry
+                             {:nick     nick
+                              :username (:username u)
+                              :realname (:realname u)
+                              :host     "localhost"
+                              :ts       (System/currentTimeMillis)}]
+                         (vec (take 32 (cons entry hist))))))))
           ;; Notify channel members
           (when (and clients channels)
             (let [quit-line (str ":" nick " QUIT :Quit: " reason)]
@@ -3164,13 +3177,39 @@
         [(numeric-reply client "422" ":MOTD File is missing")]
 
         (= command "WHOWAS")
-        (if (empty? params)
+        (cond
+          (empty? params)
           [(numeric-reply client "431" ":No nickname given")]
-          (let [target (first params)]
-            [(numeric-reply client "406"
-               (str target " :There was no such nickname"))
-             (numeric-reply client "369"
-               (str target " :End of WHOWAS"))]))
+          :else
+          (let [target  (first params)
+                t-lower (string/lower-case target)
+                hist    (when (:whowas components)
+                          @(:whowas components))
+                matches (when hist
+                          (filter
+                           #(= (string/lower-case (:nick %))
+                               t-lower)
+                           hist))]
+            (if (seq matches)
+              (-> (vec
+                   (mapcat
+                    (fn [{:keys [nick username realname host]}]
+                      [(numeric-reply client "314"
+                         (str nick " " (or username nick)
+                              " " (or host "localhost")
+                              " * :"
+                              (or realname nick)))
+                       (numeric-reply client "312"
+                         (str nick " " +server-name+
+                              " :papod"))])
+                    matches))
+                  (conj (numeric-reply client "369"
+                          (str target
+                               " :End of WHOWAS"))))
+              [(numeric-reply client "406"
+                 (str target " :There was no such nickname"))
+               (numeric-reply client "369"
+                 (str target " :End of WHOWAS"))])))
 
         (= command "INFO")
         [(numeric-reply client "371"
@@ -3420,7 +3459,8 @@
      :chan-modes  (atom {})
      :chan-keys   (atom {})
      :chan-limits (atom {})
-     :invites     (atom {})}))
+     :invites     (atom {})
+     :whowas      (atom [])}))
 
 (defconst- +idle-timeout-ms+
   (if-let [t (System/getenv "PAPOD_IDLE_TIMEOUT")]
@@ -3462,6 +3502,19 @@
       (finally
         ;; Clean up in-memory state FIRST (before slow I/O)
         (when-let [nick (:nick @client)]
+          ;; Record WHOWAS history for registered clients
+          (when (and (:registered? @client)
+                     (:whowas components))
+            (let [u (:user @client)]
+              (swap! (:whowas components)
+                     (fn [hist]
+                       (let [entry
+                             {:nick     nick
+                              :username (:username u)
+                              :realname (:realname u)
+                              :host     "localhost"
+                              :ts       (System/currentTimeMillis)}]
+                         (vec (take 32 (cons entry hist))))))))
           (when (:clients components)
             (swap! (:clients components) dissoc nick))
           (when (:channels components)
diff --git a/tests/integration.clj b/tests/integration.clj
index 39993dc..84f8647 100644
--- a/tests/integration.clj
+++ b/tests/integration.clj
@@ -49,7 +49,8 @@
      :chan-modes  (atom {})
      :chan-keys  (atom {})
      :chan-limits (atom {})
-     :invites    (atom {})}))
+     :invites    (atom {})
+     :whowas     (atom [])}))
 
 (defn- make-client
   "Creates a simulated client connection using piped streams.
diff --git a/tests/unit.clj b/tests/unit.clj
index 5439c71..b8fc57f 100644
--- a/tests/unit.clj
+++ b/tests/unit.clj
@@ -115,7 +115,8 @@
        :chan-modes (atom {})
        :chan-keys (atom {})
        :chan-limits (atom {})
-       :invites (atom {})})))
+       :invites (atom {})
+       :whowas (atom [])})))
 
 (defn test-network!
   [conn]
@@ -1870,6 +1871,42 @@
       (swap! (:chan-limits comp) assoc "#small" 1)
       (let [replies (handle-join ["#small"] bob comp)]
         (is (string/includes? (first replies) "471")))))
+  (testing "WHOWAS returns history after QUIT"
+    (let [c (registered-client "alice"
+              (java.io.ByteArrayOutputStream.))
+          components (test-components)
+          comp (assoc components
+                 :clients (atom {"bob" {:client-atom
+                                        (atom
+                                         {:nick "bob"
+                                          :registered? true
+                                          :user
+                                          {:username "bobu"
+                                           :realname "Bob"}})
+                                        :w
+                                        (java.io.ByteArrayOutputStream.)}}))]
+      ;; Bob quits
+      (let [bob (:client-atom (get @(:clients comp) "bob"))]
+        (replies-for! {:command "QUIT" :params [":bye"]}
+                      bob comp))
+      ;; Alice WHOWAS bob — gets history
+      (let [replies (replies-for!
+                      {:command "WHOWAS" :params ["" "bob"]}
+                      c comp)]
+        (is (>= (count replies) 2))
+        (is (some #(re-find #" 314 " %) replies))
+        (is (some #(re-find #" 369 " %) replies))
+        (is (not (some #(re-find #" 406 " %) replies))))))
+  (testing "WHOWAS for unknown nick returns 406"
+    (let [c (registered-client "alice"
+              (java.io.ByteArrayOutputStream.))
+          components (test-components)]
+      (let [replies (replies-for!
+                      {:command "WHOWAS"
+                       :params ["" "neverexisted"]}
+                      c components)]
+        (is (some #(re-find #" 406 " %) replies))
+        (is (some #(re-find #" 369 " %) replies)))))
   (testing "+k key blocks JOIN with 475"
     (let [{:keys [test-network-id] :as components}
           (test-components-with-network)